Editing XOR linked list (section)

==Features==
* Two XOR operations suffice to do the traversal from one item to the next, the same instructions sufficing in both cases. Consider a list with items <code>{…B C D…}</code> and with R1 and R2 being [[Processor register|registers]] containing, respectively, the address of the current (say C) list item and a work register containing the XOR of the current address with the previous address (say C⊕D).  Cast as [[System/360]] instructions:

 X  R2,Link    R2 <- C⊕D ⊕ B⊕D (i.e. B⊕C, "Link" being the link field
                                   in the current record, containing B⊕D)
 XR R1,R2      R1 <- C ⊕ B⊕C    (i.e. B, voilà: the next record)

* End of list is signified by imagining a list item at address zero placed adjacent to an end point, as in <code>{0 A B C…}</code>. The link field at A would be 0⊕B. An additional instruction is needed in the above sequence after the two XOR operations to detect a zero result in developing the address of the current item,
* A list end point can be made reflective by making the link pointer be zero. A zero pointer is a ''mirror''. (The XOR of the left and right neighbor addresses, being the same, is zero.)